Multivalue no variable

{
    "log": {
      "entries": [
        {
          "request": {
            "method": "GET",
            "url": "https://test.loadimpact.com/users"
          }
        },
        {
          "request": {
            "method": "POST",
            "url": "https://httpbin.org/post",
            "comment": "Post about found images",
            "postData": {
              "mimeType": "application/x-www-form-urlencoded",
              "params": [
                {
                  "name": "a",
                  "value": "Check out these cute pictures"
                },
                {
                  "name": "a",
                  "value": "asdasdsada"
                }
              ]
            }
          }
        }
      ]
    }
}